Uses library of optimized math routines. You must use default rounding mode by specifying -fround=nearest when you use this option.
This option uses a math routine library optimized for performance and usually generates faster code. The results might be slightly different from those produced by the normal math library; if so, they usually differ in the last bit.
The order on the command line for this library option is not significant.
This option is implied by the –fast option.
–fast, –xnolibmopt, -fround